The present invention relates generally to intraluminal or intravascular catheters used to deliver radiation inside a living body. More specifically, the present invention relates to a radioactive source comprising an elongated wire.
Intravascular diseases are commonly treated by relatively non-invasive techniques such as percutaneous transluminal angioplasty (PTA) and percutaneous transluminal coronary angioplasty (PTCA). These therapeutic techniques are well known in the art and typically involve use of a guide wire and a balloon catheter, possibly in combination with other intravascular devices. A typical balloon catheter has an elongated shaft with a balloon attached to a distal end and a manifold attached to a proximal end. In use, the balloon catheter is advanced over the guide wire such that the balloon is positioned adjacent a restriction in a diseased vessel. The balloon is then inflated and the restriction in the vessel is opened.
Vascular restrictions that have been dilated do not always remain open. In approximately 30% of the cases, a restriction reappears over a period of months. The mechanism of this restenosis is not understood. The mechanism is believed to be different from the mechanism that caused the original stenosis. It is believed that rapid proliferation of vascular smooth muscle cells surrounding the dilated region may be involved. Restenosis may be in part a healing response to the dilation, including the formation of scar tissue.
Intravascular radiation using a radioactive source has been proposed as a means to prevent or reduce the effects of restenosis. In particular, during or shortly after treatment, the blood vessel tissue concerned is irradiated with ionizing radiation, in particular xcex2 and/or xcex3 radiation, so that a subsequent recanalization treatment is no longer necessary, or in any event, a much longer period of time elapses before such treatment is necessary.
In order to bring the radioactive source to the stretched blood vessel tissue, the source must be pushed, at least in part, through the catheter in the blood vessel. However, in many cases, the blood vessels, such as those of the coronary artery around the heart, comprise short or tight turns.
There is thus an on-going need to improve the design of radioactive sources used in intravascular treatments. The radioactive source should be flexible enough to permit displacement through a catheter in a blood vessel, while retaining sufficient stiffness to ensure that the radioactive material is positioned as desired for treatment.
A radioactive source for use in intravascular treatment includes an elongated support wire having a first diameter and an integral distal end having a second diameter. The second diameter is less than the first diameter. A spirally wound ribbon is disposed about the distal end. The ribbon is sheet-like having an outwardly facing major surface. The ribbon includes a radioactive material.
A second broad aspect of the present invention is a radioactive source that includes an elongated support wire having a first diameter and a distal end having a second diameter. The second diameter is less than the first diameter. A plurality of spaced-apart toroidal elements are disposed on the distal end. Each toroidal element includes radioactive material.
A third broad aspect of the present invention is a radioactive source that includes an elongated support wire having a first diameter and a distal portion having a second diameter. The second diameter is less than the first diameter, and a radioactive material covering is provided over the distal portion.